Effect of different sintering additives on the reaction-bonded Si_3N_4/SiC composite ceramics

摘要

Effect of different sintering additives on reaction-bonded Si_3N_4/SiC composite ceramics under pressureless was investigated. Si_3N_4/SiC composite ceramics were sintered at the temperature 1550°C under nitrogen atmosphere with different sintering additives Y_2O_3, Y_2O_3: Al_2O_3=1:1, Y_2O_3: Mg_2AlO_4: Mg_3(Si_4O_(10))(OH)_2: SiO_2=5:2:1:1, and ZrO_2 by using SiC with different particle sizes, and Si as raw materials. The phases, microstructure and mechanical property were characterized by XRD, SEM, and compressive strength test. The results demonstrated that when the particle gradation consisted of silicon carbide of 74 μm (5 wt.%), 44 μm (10 wt.%) and 0.5 μm (30 wt.%) and silicon powder of 74 μm (42 wt.%), the more dense samples with the bulk density of 2.43 g/cm~3 and the higher compressive strength of 324 MPa could be obtained when Y_2O_3 was used as sintering additives.